WO 2005/105386 discloses an impact tool in the form of an electric hammer drill having a vibration reducing mechanism. In this known electric hammer drill, a dynamic vibration reducer is provided as a means for reducing vibration caused by hammering operation in the axial direction of a hammer bit, and a weight of the dynamic vibration reducer is forcibly driven by utilizing swinging movement of a swinging member in order to reduce vibration caused during hammering operation.
With the above-described construction, regardless of magnitude of vibration acting upon the impact tool, the dynamic vibration reducer can be steadily operated. In this known impact tool, however, further improvement is required in vibration reducing performance.